Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be accessed by various types of access terminals adapted to facilitate wireless communications, where multiple access terminals share the available system resources (e.g., time, frequency, and power). Examples of such wireless communications systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems and orthogonal frequency-division multiple access (OFDMA) systems.
In some instances, access terminals may utilize include a slotted mode, or a discontinuous receive (DRx) mode, as a power-saving feature. Here, the slotted mode is a power-saving feature where the access terminal periodically turns off and on certain power-intensive circuitry, such as the RF power amplifier at the receiver. The circuitry is turned on at a known interval, so that the access terminal can listen for paging messages or other downlink information only when that information might be transmitted to the access terminal. Generally, if there is nothing transmitted for that modem, its receiver is turned back off until the next cycle. This slotted mode can occur in idle states, and in traffic states, depending on the technology used.
To listen for the paging messages, when the modem wakes up from its low-power mode and turns on its receiver, it must first search for and acquire a pilot transmitted by the base station. The goal is to acquire the pilot and start demodulating before any pertinent data arrives on the forward link (also called the downlink).